Miniature watering devices such as dripper or spray units are used extensively for the application of water to plants. Typically, these devices will be attached or inserted into a common hose or pipe and deliver water according to a preset flow rate or in some cases the devices may be adjustable. As the water pressure being delivered to the watering device will often vary, many of these devices will include a pressure compensating capability which attempts to provide a uniform output flow rate of water from the device irrespective of the input pressure of water being fed to the watering device.
Often this pressure compensating capability only functions over a relatively narrow range of input water pressure. If mains or input water pressure increases unexpectedly outside of this range, the pressure compensating capability of the watering device is overwhelmed causing the watering device to fail. For miniature watering devices having multiple outlets the required input pressure will already be high, thereby exacerbating this effect. Accordingly, in many cases a further flow or pressure regulator must be incorporated into the irrigation system.
Flow or pressure regulators are devices that aim to deliver constant outlet pressure under varying input flow conditions over a range of input flow rates. However, as a pressure regulator in itself only functions over a limited range of flow rates, the output capacity of the watering devices will also need to be matched with the capacity of the pressure regulator. As a consequence, any change in the irrigation system will need to take into account the capacity of the pressure regulator. This adds extra complexity to this task, particularly in the context of a domestic irrigation system where a person not having any specialised training will be carrying out the modifications. Furthermore, the incorporation of a pressure regulator in an irrigation system adds extra expense and another point of potential failure which may occur either in the device itself or in the related extra joints and fittings required to incorporate the pressure regulator into the irrigation system. There is therefore a need for a watering device that is capable of performing under an increased range of inlet water pressures.